Oil investors have grown wary of another oil price rally as they have doubts about whether U.S. producers would be able to rein in production growth, Goldman Sachs warned in a note.

The investment bank said that even though tailwinds such as global economic growth projections, the possibility of supply disruptions, and discipline among U.S. producers remains, there were misgivings about the last factor.

“Most importantly, investors remain unconvinced U.S. producer discipline will hold,” Goldman wrote in the note, adding, “That supply growth needs to be constrained voluntarily, even in the face of a more constructive demand outlook still leaves investors more focused on other metals and mining, where there is greater confidence in China policy-driven supply constraints”…